Keflex

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Keflex

To reduce the development of drug-resistant bacteria and
maintain the effectiveness of Keflex and other antibacterial drugs, Keflex
should be used only to treat or prevent infections that are proven or strongly suspected
to be caused by bacteria.

DRUG DESCRIPTION

Keflex® Capsules
(Cephalexin Capsules, USP) is a semisynthetic cephalosporin antibiotic intended
for oral administration. It is 7-(D-α-Amino-α-phenylacetamido)-3-methyl-3-cephem-4-carboxylic
acid monohydrate. Cephalexin has the molecular formula C16H17N3O4S•H2O
and the molecular weight is 365.41.

Cephalexin has the following structural formula:

The nucleus of cephalexin is related to that of other
cephalosporin antibiotics. The compound is a zwitterion; i.e., the molecule
contains both a basic and an acidic group. The isoelectric point of cephalexin
in water is approximately 4.5 to 5. The crystalline form of cephalexin which is
available is a monohydrate. It is a white to cream colored crystalline solid
having a bitter taste. Solubility in water is low at room temperature; 1 or 2
mg/mL may be dissolved readily, but higher concentrations are obtained with
increasing difficulty.

The cephalosporins differ from penicillins in the
structure of the bicyclic ring system. Cephalexin has a D-phenylglycyl group as
substituent at the 7-amino position and an unsubstituted methyl group at the 3-position.

What are the precautions when taking cephalexin (Keflex)?

Before taking cephalexin, tell your doctor or pharmacist if you are allergic to it; or to penicillins or other cephalosporins (such as cefpodoxime); or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.